One of the principal factors implicated in the cariogenicity of Streptococcus mutans is the enzyme; glucosyltransferase. The ultimate goal of this project is to gain a more thorough understanding of the role of the Streptococcus mutans GS-5 derived glucosyltransferase in adherence, cell aggregation, and cariogenesis. Using recombinant DNA technology to clone the gene coding for this enzyme, which synthesizes water insoluble glucan, it will be possible to study the regulation of expression on the nucleotide sequence level. More importantly, it will be possible, using site-directed, in vitro mutagenesis with subsequent transfer of the mutation to S. mutans GS-5, to create a series of well-characterized glucosyltransferase mutants in isogenic backgrounds. Using these mutants in both in vitro and in vivo studies it will now be possible to assess the role of both glucosyltransferase and insoluble glucan in adherence, aggregation, and cariogenesis without the concern of other factors influencing the results. From these studies, an understanding of the pathogenesis of dental caries will be realized and information will be gained that can aid in the prevention and eventual elimination of caries.